A tiny java-program for language training

WordTrainer.java

/**
 * WordTrainer 2008-12-02
 * Simple language training in Java. This program accepts text-files
 * containing where each line contains two words in two diffrent languages
 * separated by a comma (,). The first line follows the same format but
 * specifies the language.
 *
 * Sample gloss-file:
 * Engelska,Svenska
 * cloud,moln
 * world,värld
 * day,dag
 * stay,stanna
 * mysterious,mysterisk
 * 
 * This application uses swing and has no external dependencies, besides 
 * the standard java runtime.
 *
 * All comments are welcome.
 *
 * @author Emil Hernvall <aderyn@gmail.com>
 * @license PD - No rights reserved.
 **/

import java.io.*;
import java.util.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.List;

/**
 * Main class.
 * Static main()-method contains program flow.
 **/
public class WordTrainer
{
	/**
	 * A simple dialog that allows the user to select the language of the displayed
	 * glosses. 
	 */
	private static class LanguageSelector extends JDialog implements ActionListener
	{
		private int choice = 0;
		JRadioButton lang1;
		JRadioButton lang2;

		/**
		 * Initializes the dialog and creates the gui elements.
		 * 
		 * @param String l1 - First language
		 * @param String l2 - Second language
		 **/
		public LanguageSelector(String l1, String l2)
		{
			JPanel pane = new JPanel();
			pane.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
			pane.setLayout(new BoxLayout(pane, BoxLayout.Y_AXIS));

			JLabel label = new JLabel("Please select the primary language:");
			pane.add(label);

			ButtonGroup group = new ButtonGroup();
			lang1 = new JRadioButton(l1);
			lang1.setSelected(true);
			group.add(lang1);
			pane.add(lang1);
			lang2 = new JRadioButton(l2);
			group.add(lang2);
			pane.add(lang2);

			JButton btnSelect = new JButton("Select");
			btnSelect.addActionListener(this);
			pane.add(btnSelect);
			JButton btnExit = new JButton("Exit");
			btnExit.addActionListener(new ActionListener() {
				public void actionPerformed(ActionEvent e) {
					System.exit(0);
				}
			});
			pane.add(btnExit);

			add(pane);

			setTitle("Language");
			setVisible(true);
			pack();
		}
		
		/**
		 * Implementation of the ActionListener-interface. Invoked by
		 * the Select-button. Stores the users choice of language and
		 * notifies the main thread that the user has made her/his
		 * choice.
		 **/
		public synchronized void actionPerformed(ActionEvent e)
		{
			if (lang2.isSelected()) {
				choice = 2;
			} else {
				choice = 1;
			}
			this.notify();
			setVisible(false);
		}

		/**
		 * Returns 1 or 2 depending on the choice of language.
		 **/
		public int getChoice()
		{
			return choice;
		}
	}

	/**
	 * A very simple frame that displays the results of the quiz in
	 * a text box. It also provides a button to close the frame and
	 * exit the application.
	 **/
	private static class ReportFrame extends JFrame implements ActionListener
	{
		/**
		 * Initializes the frame and creates the gui elements.
		 **/
		public ReportFrame(String text)
		{
			super();

			JPanel pane = new JPanel();
			pane.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
			pane.setLayout(new BoxLayout(pane, BoxLayout.Y_AXIS));

			JTextArea txtInfo = new JTextArea(text);
			txtInfo.setEditable(false);

			pane.add(txtInfo);
			pane.add(Box.createVerticalStrut(5));

			JButton exitButton = new JButton("Exit");
			exitButton.setMinimumSize(new Dimension(100,20));
			exitButton.addActionListener(this);

			pane.add(exitButton);

			add(pane);

			setTitle("Result");
			setVisible(true);
			setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
			pack();
		}

		public void actionPerformed(ActionEvent e)
		{
			System.exit(0);
		}
	}

	/**
	 * Class containg two words in two different languages.
	 **/
	private static class Gloss
	{
		public String l1;
		public String l2;
	}

	/**
	 * The class is never instantiated.
	 **/
	private WordTrainer()
	{
	}

	/**
	 * Application entry-point.
	 **/
	public static void main(String args[])
	throws Exception
	{
		// Avoid the ugly java look and feel, if possible.
		try {
			UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
			JFrame.setDefaultLookAndFeelDecorated(true);
		} catch(Exception e) {
			System.out.println("Error setting native LAF: " + e);
			System.exit(0);
		}

		// Display a file dialog if needed, or retrieve file name
		// by checking the application argument list.
		String file;
		if (args.length == 0) {
			FileDialog fd = new FileDialog((Frame)null);
			fd.setVisible(true);
			file = fd.getFile();
			
			// Exit on abort.
			if (file == null) {
				System.exit(0);
			}
		} else {
			file = args[0];
		}

		// Ensure that the provided file exists. Exit if not.
		if (!new File(file).exists()) {
			JOptionPane.showMessageDialog(null, "Failed to find file!");
			System.exit(0);
		}

		// Open the provided file for reading.
		FileReader fileReader = new FileReader(file);
		BufferedReader reader = new BufferedReader(fileReader);

		// Read the first line containing the language key.
		String legend = reader.readLine();
		if (legend == null) {
			JOptionPane.showMessageDialog(null, "First line should follow the format \"firstlang,secondlang\".");
			System.exit(0);
		}

		String[] langs = legend.split(",");
		if (langs.length != 2) {
			JOptionPane.showMessageDialog(null, "First line should follow the format \"firstlang,secondlang\".");
			System.exit(0);
		}

		// Read the rest of the glosses from the file, store them in a linked list for easy
		// sequential access.
		LinkedList<Gloss> glossary = new LinkedList();
		String line;
		while ((line = reader.readLine()) != null) {
			String[] lineSplit = line.split(",");
			if (lineSplit.length != 2) {
				JOptionPane.showMessageDialog(null, "Lines should follow the format \"firstlang,secondlang\".");
				System.exit(0);
			}

			Gloss gloss = new Gloss();
			gloss.l1 = lineSplit[0];
			gloss.l2 = lineSplit[1];
			glossary.add(gloss);
		}

		// Randomize the order.
		Collections.shuffle(glossary);

		// Done reading. Close the readers.
		reader.close();
		fileReader.close();
		
		// Display the selection box.
		String firstLang = langs[0];
		String secondLang = langs[1];
		LanguageSelector ls = new LanguageSelector(firstLang, secondLang);
		synchronized(ls) {
			// Wait until the user has made a selection.
			ls.wait();
		}

		// Retrieve the users choice.
		int primLang = ls.getChoice();

		// Main query loop
		int done = 0, correct = 0;
		LinkedList<Gloss> invalid = new LinkedList();
		LinkedList<Gloss> valid = new LinkedList();
		while (glossary.size() > 0)
		{
			// Pick a gloss from the linked list. Query the user.
			Gloss gloss = glossary.poll();
			String text = "What's the translation of \"";
			if (primLang == 2) {
				text += gloss.l2;
			} else {
				text += gloss.l1;
			}
			text += "\"?";
			String res = JOptionPane.showInputDialog(null, text);

			// Check if the answer is correct.
			if (primLang == 2) {
				if (gloss.l1.equals(res)) {
					correct++;
					valid.add(gloss);
				} else {
					invalid.add(gloss);
				}
			} else {
				if (gloss.l2.equals(res)) {
					correct++;
					valid.add(gloss);
				} else {
					invalid.add(gloss);
				}
			}

			done++;
		}

		// Display results
		String endResult = "You got " + correct + " correct from a total of " + done + ".\n\n";
		endResult += "Failed: \n";
		for (Gloss gloss : invalid) {
			endResult += gloss.l1 + " - " + gloss.l2 + "\n";
		}

		endResult += "\nCorrect: \n";
		for (Gloss gloss : valid) {
			endResult += gloss.l1 + " - " + gloss.l2 + "\n";
		}

		ReportFrame report = new ReportFrame(endResult);
	}
}